In compliance with European Union (EU) legislation for visitors from the EU, Schlumberger requests your permission to place cookies on your computer to both improve your experience and to help us improve our website. To find more about these cookies, see the Schlumberger General Website Privacy Statement.

mud return line

Also known as flowline, the large-diameter metal pipe that connects the bell nipple under the rotary table to the possum belly at the mud tanks. The flowline is simply an inclined, gravity-flow conduit to direct mud coming out the top of the wellbore to the mud surface-treating equipment. When drilling certain highly reactive clays, called "gumbo," the flowline may become plugged and require considerable effort by the rig crew to keep it open and flowing. In addition, the flowline is usually fitted with a crude paddle-type flow-measuring device commonly called a "flow show" that may give the driller the first indication that the well is flowing.